These specifications are intended to describe and define the minimum requirements for a self-contained,
drum type, transit concrete mixer installed on a hook lift frame capable of quick installation and removal from
the chassis employing a hook lift on the chassis. The mixer shall be capable of agitating and transporting 3.5
cubic yards of concrete at a reasonable slump while firmly attached to the chassis. The unit features a
planetary reduced hydraulic drive, hydraulic pump system powered by a 30 HP diesel engine, pressurized water
system for slump control and wash down. Operator controls are situated on the rear of the unit to control drum
speed /direction, discharge chute height and engine throttle control. The mixer is equipped with removable
chutes with a reach of over 12’ for placement of concrete. The drum is capable of 18 RPM at 2,500 engine RPM
in both directions.

The mixer is powered by a Kubota model V1305 diesel engine. The engine is rated at 29.1 continuous
horsepower and is tier 4 emission approved. The engine features a 12VDC charging and starting system, 15
gallon fuel tank and Murphy low oil pressure/high water temperate automatic shutdown system. The engine will
be equipped with a two speed electronic throttle with controls at the rear operators control panel. The engine
master control panel will feature a keyed switch, override switch for Murphy shutdown, tachometer and engine
hour meter. The engine will further be equipped with a 575 CCA battery and intake manifold glow plugs for cold
starting.

1/4” thick spun steel drum head, with reinforced machined flange to
mount gear drive. Fabricated from 3/16 high-strength carbon steel, the
drum is fully welded inside and out. A 1-1/4” thick X 2-1/2” wide
carbon steel track ring is welded to the rear of the drum.
Charging/discharge fins: two separate helix, 2.5 revolution pitch over
length of drum, 3/16 high strength carbon steel. In the belly of the
drum, the fins are 12” tapering to 8” at the discharge. Fins feature
hardened steel rebar welded to the tips and fold over fins at discharge
end of the drum. The fins are fully welded to drum and equipped with
wash holes approximately 12” apart. Man way: one 22” X 28” is located on
front of drum to access interior. The cover is bolted to main drum with
twenty two ½” bolts. The rear of the drum is supported by two carrier
bearings, mounted on an adjustable pedestal. The bearings feature a
hardened exterior with tapered roller bearings and lip seals for long
life. The bearings are further protected by a felt disk on each side to
prevent direct water spray. Each bearing features a convenient panel
mounted grease whip.

Hook Lift Frame

The hook lift frame shall be a heavy duty tubular steel construction, 2” X 8” long sils, 2” X 6” “A”
frame with 1/2” A36 gussets and tubular steel cross members. The frame shall be approximately 13’6” in length.
The frame shall be equipped with two each 8” all steel wheel assemblies on the rear rigidly welded to the
frame. The concrete mixer frame shall be electrically welded to the hook lift frame creating a unitized
framework. The frame shall feature two ratchet strap assemblies welded to the front of the frame to secure the
mixer frame to the chassis frame. The ratchet straps will be 3” wide nylon and rated a minimum capacity of
3000# each.

Discharge Chute

A 24” wide discharge chute at the drum, tapering to 12” wide on a rotating pedestal is provided. One each
permanently mounted extension chute 34” long and two each removable chutes 34” long are standard equipment. A
structural steel chute holder is provided welded to the hook lift frame and features rubber straps to hold
chutes while in transit. The discharge chute is equipped a single acting telescoping hydraulic cylinder, self
contained 12VDC hydraulic pump and switch. The discharge chute cylinder is controlled by a toggle switch
located at the control panel. The discharge chute is capable of pivoting 180 degrees and features a manual
lock assembly with safety transport lock.

Access Platform

Structural steel tube ladder leads to a grated steel platform with a square tube railing on three sides. The
ladder shall fold and lock to permit loading and unloading via hook lift.

Water System

The unit shall feature an 75 gallon pressured water tank of carbon steel construction. The tank will be
removable installed on saddles rigidly welded to the hook lift frame. The saddle straps will we equipped with
vibration proof rubber channels. The water tank will feature a flapper style lid assembly with replaceable
gasket. The tank will be equipped with a 3/4” “Y” type strainer with removable screen assembly. The
water system will get pressurized air from the air brake system on the truck chassis. The air system will be
equipped with a check valve to prevent reverse flow of air into chassis air brake system, air regulator, ASME
pressure relief valve. All fittings connecting the air pressure lines shall be DOT approved fittings. The
water system will further be equipped with a valve and hose to direct water directly to the drum for slump
control. The until will also be equipped with a 25’ wash down hose with adjustable nozzle. Note, chassis must
be equipped with air brakes. If chassis is not equipped with air brakes select “Zero Pressure Water System
Option”.

Controls

Electronic controls for speed and direction of drum, power discharge chute control and engine throttle
control are located at rear of the mixer in a waterproof aluminum box. The controls shall feature MIL spec
waterproof switches with vinyl boot covers. The electrical system shall be equipped with a replaceable 30 amp
fuse.

Finish

Unit is completely coated with self-etching primer and finished coated with a two component urethane finish.
Mixers are standard one color white.

Parts and Service

Manufacturer carries a complete inventory of parts available for shipment within 24 hours.

One complete operators & parts manual will be supplied with the unit. All operators of the mixer should
read the operators manual in full prior to operation of the mixer. Serious injury or death may result from the
improper or misuse of the mixer body. Questions concerning the operation of the Shortstop Mixers call (937)
325-9851, email: sales@ernestindustries.com

Specifications

In our continuing effort to make improvements, specifications are subject to change without notification.

Chassis

30,000 to 33,000 GVW chassis is recommended.

Estimate Payload Requirements:

Hook lift frame/Shortstop 3.5 Mixer

5,250 lb

75 gallons water

664 lb

3.5 Cubic yards concrete at 3,800#/yard

13,300 lb

Total

19,150 lb

General

The standard Shortstop 3.5 mixer is operated with a closed loop hydraulic system, the hydraulic pump
features a flow and direction control on the pump and the hydraulic pump’s sole purpose is to control the
direction and speed of the mixer.

It is possible to operate the drum in an open loop environment. Open loop hydraulic systems are standard
equipment on typical chassis driven PTO dump trucks, state dump/plow trucks and in general hydraulic systems
found on most hook lift chassis. Additional hydraulic control valves are required and field adjustment of the
hydraulic equipment will be necessary at installation. The open loop configuration is less efficient and
controlling the speed and direction of the drum can be sluggish. We strongly recommend the closed loop system
when possible.

A factory direct technician shall be provided for a period of two working days to instruct the
contractor/city personnel in the operation and maintenance of the mixer. Strongly recommend if you do not have
experience in the operation of a concrete mixer.

OE3.5-1

Not applicable for hook lift configuration.

OE3.5-2

Night lights, 4 each high output halogen lights to illuminate rear
discharge area and charging chute.

Wireless remote controls in lieu of hard wired control box. A water proof receiver will be mounted on the
mixer frame under the rear tower. A transmitter shall be provided to control the speed/direction of the drum
and power discharge chute. The receiver will get power from the 12VDC charging system on the diesel engine and
the transmitter shall be powered by two AA batteries. The operating range is 250’.